Capricornus

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Capricornus is a constellation in the southern hemisphere. It is one of the constellations of the zodiac. Capricornus represents a sea-goat, a mythical creature that is half goat, half fish. Its name means "horned male goat" or "goat horn" in Latin. Like other zodiac constellations, Capricornus was first charted by the Greek astronomer Ptolemy in the 2nd century.

The constellation was well known in Sumerian and Babylonian cultures. Sumerians called it Suhur-mash-sha (the goat-fish), while Babylonians identified it with the god Ea, who had the upper body of a human and lower body of a fish. The Greeks later renamed it to Aegoceros (goat-horned) and associated it with Pan, god of nature, who also had a goat's legs and a horn.

In Greek mythology, Pan earned his place in the sky after helping Zeus and other gods defeat the Titans. When Pan was attacked by the monster Typhon, he jumped into the river Nile and transformed himself into an goat to escape detection. As he was half-way submerged, he took the form of a fish from the waist down. In another Greek tale, the constellation represents Amalthaea, the goat that nursed Zeus as an infant.

Arabs, Turks, Persians and Syrians all associated Capricornus with a goat. In some parts of the Orient, Capricornus was called the "Southern Gate of the Sun," because it was the constellation in which the Sun reached its lowest point on the ecliptic.

The constellation Capricornus occupies an area of 414 square degrees and contains two stars with known planets. It can be seen at latitudes between +60° and -90° and is best visible at 9 p.m. during the month of September. It lies in a region called the Sea or the Water, which is a part of the sky that contains many water-related constellations: Aquarius (the Water-bearer), Cetus (the Whale), Pisces (the Fishes), Eridanus (the Great River), and others.

The tropic of Capricorn, the latitude at which the Sun appears overhead at noon on the winter solstice, which occurs between December 21 and 22, got its name because in Greek times the Sun was passing through Capricornus on this date. In tropical astrology, Capricorn’s rule still begins on the first day of winter. The Tropic of Capricorn, however, has since moved to the constellation Sagittarius.

Capricornus is the second faintest of the zodiac constellations, after Cancer. It has several bright stars that form a celestial triangle: [1583] alpha-2 Capricorni, [1582] beta Capricorni and [1587] omega Capricorni.

[1581] delta Capricorni, also known as Deneb Algedi ("the goat’s tail") and Scheddi, is the brightest star in the constellation, with a magnitude of 2.85. It is a four-star system with a white giant for the primary component.

[1582] beta Capricorni or Dabih ("the butcher") is the second brightest star in Capricornus. It is another multiple star system. In a small telescope, it appears as a binary star, but each of the two main components – beta-1 Capricorni or Dabih Major and beta-2 Capricorni or Dabih Minor - are in fact made up of several stars. Dabih Major contains an orange bright giant and a blue-white dwarf. Dabih Minor is a binary star with an A0-giant for a primary and a companion with an atmosphere unusually rich with mercury and manganese.

Alpha Capricorni is also known as Algedi or Giedi, from the Arabic word for "the goat." It is a multiple star that consists of two yellow and orange stars, both binaries themselves, and can be seen by the naked eye. [1583] alpha-2 Capricorni has a magnitude 11 companion and [1589] alpha-1 Capricorni, the fainter of the two, has a wide magnitude 9 companion.

[1587] omega Capricorni, occasionally referred to as Baten Algiedi ("belly of the goat"), is a red giant with a magnitude of 4.12, about 630 light-years distant from Earth. It is a variable star. Both its absolute magnitude and luminosity constantly fluctuate.

[1584] gamma Capricorni, also known as Nashira ("bearer of good news"), is a blue-white giant with a magnitude of 3.69.

[1585] zeta Capricorni or Marakk ("loins") is a magnitude 4 binary star with a yellow supergiant for a primary component and a white dwarf for its companion. The supergiant, zeta Capricorni A, is a prototypical example of a Barium star. The zeta Capricorni system lies approximately 398 light-years from Earth.

Capricornus also contains a magnitude 8 globular cluster, Messier 30 or NGC 7099. It can be spotted near [1585] zeta Capricorni in a small telescope. The star cluster has a compressed centre, with two short rays of stars appearing north-west and irregular streams of stars spiraling from the northern edge toward the east.